Patent GB-420419-A (GB)
Title: Improvements in or relating to apparatus for timing races or other events
IPC: G03B15/00
Filed: 1934-05-30
Abstract: 420,419. Chronometers; illuminating dials; stop mechanism. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A.-(Assignees of Morton, E. R. ; 344, West 12th Street, New York, and Hibbard, F. H.; 11, Valley Road, Mountain Lakes, New Jersey, both in U.S.A.) May 30, 1934, No. 16103. Convention date, Aug. 2, 1933. [Class 139] In an apparatus for timing races and other events, a chronometer with several concentric dials geared together is driven through a clutch from a synchronous electric motor supplied with current, the periodicity of which is regulated by a tuning fork the clutch being operated by condenser discharges controlled by start and stop keys. A motion picture camera may take photographs of the finish of the race and of the chronometer dials on the same film in the manner described in Specification 410,630. The concentric dials 2, 3 and 4, Figs. 4 and 8, are all driven from the toothed wheel 5 at different speeds so as to show, for example, minutes, seconds, and hundredths of a second. The central spindle 8 and the concentric tubes 15, 24 are geared together and connected respectively to the dials 4, 3, 2 by spring frictional means. The dials are viewed through a slot in a disc 38 which may be rotated to reset the dials to zero, by ratchet and pawl mechanism. The chronometer is started and stopped by electromagnetic means actuated by the discharge of condensers controlled by switches. The shaft 113, Fig. 8, carries at one end the pinion 118 meshing with the chronometer wheel 5 and at the other end the ratchet clutch member 105, and is moved lengthwise into engagement either with the fixed ratchet ring 102 or with the ratchet ring 101 which is rotated continuously at constant speed by the synchronous motor M. The armature 114 secured to the shaft 113 is attracted towards but not into contact with one or the other of the polepieces 107 according to the direction in which current flows momentarily through the windings of the polepieces. A permanent magnet arranged parallel with the polepieces ensures that the armature is held magnetically in either of the positions to which it is moved. The condensers 121, 122, which discharge as required in either direction through the polepiece windings, are charged from the amplifier 120 through a resistance 126 which prevents too rapid charging, and also prevents the amplifier from being affected by the discharge current. When the starting switch 123 is closed momentarily, condenser 122 applies a sudden positive potential to the windings of the polepieces 107 which moves the armature 114 and shaft 113 so that the clutch member 105 engage the rotating clutch member 101. The momentary movement of the stop switch 124 towards the right, discharges condenser 121 in the opposite direction and moves the clutch member 105 into contact with the fixed ratchet member 102. The starting pistol 125 may be used instead of the starting switch 123. The frequency of the current supplied to the motor M is controlled by a tuning fork 134 having driving coils 133 and pick up coils 140, the current developed in the latter being amplified to operate the motor. The tuning fork and coils are enclosed in a casing 145 which is maintained at a sub. stantially constant temperature by a heating coil 146 supplied with current from the amplifier 120 through a switch 149 operated by a solenoid under the control of a thermostat 151. A lamp 166 in the casing 165 illuminates the dials 2, 3, 4.